The Spanish prepositions por and
para tend to be difficult for Spanish students, because they can
- but don't always - both mean for.
Por is considerably more common, so in theory, you might be able
to get away with just memorizing the uses for
para
and then using por for everything else.
In reality, it's good to learn the rules, so here they are.

This lesson is divided into two sections. In the first, the uses of
por and para
are compared and contrasted. In the second, the uses of
por which don't have a complementary
para usage are explained.

Por vs Para

Por

Para

Location/Movement: General
vs Specific

General location or movement:
by (way of), through, via, around, near

Specific destination:to, toward

Hay mucha gente por aquí.

There are a lot of people here.

Van para el colegio.

They're going to(ward) school.

Voy a Madrid por Bilbao.

I'm going to Madrid via Bilbao.

Voy en tren para Madrid.

I'm going by train to Madrid.

Sal por esta puerta.

Go out through this door.

Está por el norte.

It's to the north.

Time: Duration/Point in
time vs Deadline

Duration, inexact point in time:
for, in, around

Deadline, time by which:
by, before, for

Estudié por 3 horas.

I studied for three hours.

Lo haré para mañana.

I'll do it by tomorrow.

por la mañana
por la tarde
por la noche

in the morning
in the afternoon
in the evening

Termínelo para el lunes.

Finish it before Monday.

Te veré por Navidad.

I'll see you around Christmastime.

Reasons: Cause vs Purpose

Cause, Motive:
out of, for (the sake of), because (of), due to, in support of